Epson C824431 Manual page 16

Table 7. Flag polarity selection
Jumper
JNOR
J2
JREV
Note
Either the JNOR or JREV jumper must be connected.
MARK (do not
accept data) =
ON
Current ON
MARK (do not
OFF
accept data) =
Negative EIA level
Function
OFF
ON
12
MARK (do not
accept data) =
Current OFF
MARK (do not
accept data) =
Positive EIA level